In-line roller skating is a fast growing, recreational activity. Growing along with that skating activity of the general population is speed skating wherein competitors race against each other and the clock. In-line competitive speed skating has reached a popularity level where it is scheduled to be a trial event at the 1992 Olympics to be held in Barcelona, Spain.
To build an effective speed skate requires a delicate compromise between lightweight and necessary strength to achieve torsional stiffness. Skate frame weight should be minimized since a lighter skate is easier for the speed skater to carry, and the skater expends less energy in simply carrying the skate during a race. The weight should not be reduced, however, at the expense of creating a frame that twists, bends or deforms easily as a result of skating forces generated as a result of a skating stride. Any bending, twisting or other deformation of the frame from its static position results in an energy loss that could otherwise be converted into forward momentum of the skater. All such bending, twisting or other deformation of the frame absorbs energy that the skater would otherwise utilize to propel himself. Accordingly, minimizing the weight of the frame is desirable, but only if it can be done without reducing the torsional stiffness of the frame so much as to make the frame susceptible to substantial bending, twisting or other deformation.
At least two related competitive advantages can be realized by creating a skate frame that has a reduced weight over known frames. First, a lighter frame is easier for the skater to wear and particularly so during a long race. Second, as the frame is lightened and stiffened due to new structure and material composition, it is possible to make a long racing frame while still weighing less than recreational frames. A longer frame creates a greater stroke advantage with each skating stride, and thus creates a faster, more efficient skate.
The skate frame typically used by racers is generally longer than recreational skates--121/2 to 131/2 inches from front axle center to rear axle center typically--and carries five wheels instead of the three to four wheels used with recreational skates. In general, two types of racing skate frames are presently being used. One utilizes an aluminum frame having a U-shaped cross section. Another type of frame now used has a U-channel made of laminated carbon fabrics impregnated with resin. With both the aluminum and the laminated frames, the weight of a single frame is of the order of 81/2 ounces. By contrast, lighter weight commercially available synthetic frames for recreational use are now typically made out of a lightweight glass fiber reinforced nylon material. One such frame, manufactured by the assignee of the present invention, weighs less than 7 ounces but while rotatably supporting only four wheels. Many recreational frames lack sufficient torsional stiffness to resist undesirable twisting during racing. To provide resistance to twisting, current teachings in the art would call for increasing the thickness of the side rails, resulting is an undesirable increase in the frame weight, or for providing thicker supports between opposing frame side walls, or both, but again requiring an undesirable weight increase.
Accordingly, some of the currently available racing frames resist some twisting and deformation due to skating generated forces, but they do so at the expense of utilizing materials that are heavier than the materials used in recreational skates. Thus, it would be desirable to provide a racing skate frame made of a light weight synthetic material but not at the expense of losing the stiffness of the frame. The present invention achieves a merging of synthetic material with a structurally thin but effectively reinforced lightweight frame structure so as to achieve a fast, strong and highly rigid racing frame that is less susceptible to energy inefficient deformations.